Prediction of individual response to postnatal dexamethasone in ventilator dependent preterm infants.

AIMS

To evaluate factors predictive of individual response to dexamethasone in preterm infants.

METHODS

A cohort of 74 preterm infants born between January 1993 and February 1996 was studied retrospectively. All of them had received dexamethasone to facilitate weaning from artificial ventilation. Demographic factors, ventilation parameters, and details of dexamethasone administration were recorded from the medical and nursing notes. Radiographs were assessed by one observer who was unaware of the clinical condition of the infant or the outcome. Outcome variables examined included change in ventilation index (VI) at 36-48 hours, the number of days to extubation from the start of dexamethasone, and death before extubation.

RESULTS

Most babies improved but changes in VI at 36-48 hours ranged from substantial deterioration to dramatic improvement. No identifiable factors were significantly associated with this range of response. The median time to extubation was 6 days. The 36 babies who extubated within the first 6 days were: significantly more mature; less likely to have pulmonary interstitial emphysema (PIE) or pneumothorax; and had significantly lower VIs in the 12 hours preceding dexamethasone treatment. The postconceptional age at extubation was the same whether babies were extubated within or after the first 6 days. Multiple linear regression confirmed a significant association between number of days to extubation and the three factors described above (adjusted R2 = 0.5126).

CONCLUSIONS

Individual responses to dexamethasone can be partly predicted by gestation, the presence of PIE, and the VI before dexamethasone administration.